1. Field of the Invention
The present invention relates to methods and devices used in the growth of cells in vitro, such as tissue culture growth.
2. Brief Description of the Prior Art
There has been in the last decade a dramatic increase in the knowledge and understanding of how best to exploit the ability of animal, plant or artificial cells (e.g., hybridomas) to obtain pharmacologically or diagnostically useful products.
For example, interferon is released by animal cells and inhibits viral infection. Its efficacy, however, is still not well established, principally because it has been hard to grow large quantities of the cells that produce it. Monoclonal antibodies are manufactured by hybridomas. Human monoclonal antibodies, produced by human hybridomas, can best be produced by growing the human hybridomas in culture. Urokinase, an enzyme that activates plasminogen to form the blood clot dissolving enzyme plasmin is obtained from kidney cells, preferably grown in culture. Human urokinase, the enzyme that activates plasminogen to form human plasmin can be obtained from human kidney cells, which are difficult to grow on a large scale.
The obvious promise of such cells as sources for products as those described, has motivated efforts to develop efficient large-scale cell culture systems. (See, for example, Feder and Tolbert, "The Large Scale Cultivation of Mammalian Cells", Scientific American, 248:36-43 (January, 1983)).
Generally, non-bacterial cells are fragile and complex. They are enclosed by a plasma membrane, and lack a cell wall. The nutritional requirements of animal and plant cells are quite stringent since, instead of being free-living organisms as bacteria, animal or plant cells are normally adapted to specialized life as part of an organized tissue. Their viability depends on the specialized function of many other cells and on a circulatory system that assures precisely adjusted and stable environments for each cell. Most cells, animal or plant, will not grow in suspension. They grow only when they attach themselves to a surface.
Over the years, techniques have been developed for growing cells on a small scale in the laboratory. A number of devices have been proposed for the cultivation of cells in vitro. See, for example, those described by Knazek et al., U.S. Pat. No. 4,184,922 or U.S. Pat. No. 4,220,725, Johnson et al., U.S. Pat. No. 4,317,886, Katinger et al., U.S. Pat. No. 4,259,449 or Baker et al., U.S. Pat. No. 4,321,330.
A need continues to exist for improved and efficient devices and methods for in vitro growing of cells from a variety of sources.